Discharge lamp driving device, projector, and discharge lamp driving method

A discharge lamp driving device comprising:

• a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes;
• and
• a control section configured to control the discharge lamp driving section, wherein
• the control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated,
• the first period includes a plurality of AC periods including a first AC period and a second AC period,
• a frequency of alternating current supplied in the first AC period and a frequency of alternating current supplied in the second AC period are different from one another, and
• the control section changes a total length of time of the plurality of the AC periods included in the first period.